The typical fitting on the end of a hydraulic hose connection consists of a cylindrical stem which penetrates into the interior of the hose, and fingers, usually eight, which extend longitudinally along the exterior of the hose. An outer sleeve fits over the fingers and protects the fingers from damage. In use, the fitting usually outlasts the hose, which typically bursts under prolonged use. Intact removal of a fitting from the end of a burst hydraulic hose, so that the fitting can be reinstalled on the end of a new hydraulic hose, is a difficult longstanding problem in the hydraulic hose industry. It is commonplace for hydraulic hoses to burst after a period of use under the high pressures associated with hydraulic hoses and pumps, in high pressure hydraulic equipment. Particularly in remote areas, where hydraulic hoses and pumps are used on earth moving equipment, and replacement fittings are not readily available, it is important to be able to cleanly remove a fitting from the end of a burst hydraulic hose, and to be able to reuse the fitting by installing it on the end of a new hose.
The fitting on a hydraulic hose is installed under very high pressures to ensure that the joint stands up to the high pressures exerted in the hydraulic system. Because of this, the fitting and fingers grasp the hose very securely, and it is not easy to remove the fitting from the hose, without causing damage to the fitting. If chisels are used to spread the fingers of the hydraulic fitting, scores frequently occur to the fingers, or on the internal stem. It is important in the removal of a fitting, that the fingers and the stem are not scored. Scores in the stem, in particular, cut the inside liner of the new hose, thereby leading to premature failure of the hose.
Numerous attempts have been made over the years to devise devices which will readily and cleanly remove the fittings from hydraulic hoses.
A process commonly in use for fitting removal involves cutting the hose squarely approximately 2.75" to 3.00" from the end of the fitting. A pusher is inserted into the interior of the hose. The cut hose with pusher is put into a proper size collet to retain the sleeve of the fitting while force is applied on the pusher. The force on the pusher plate compresses the hose outwardly, thereby usually causing the fingers on the fitting to flare. However, frequently the hose, when it flares out, does not expand the fingers of the fitting. The hose can be worn out due to its use. In many instances, the hose tends to burst proximate to the fitting. The required cut-off length cannot then be achieved. If the cut-off length is too short, the pusher plate will contact the end of the hose stem and the eight fingers, and usually damage them, if force is applied.
Scudieri, U.S. Pat. No. 3,130,493, Apr. 28, 1964, shows a collar which fits over a hydraulic hose and when a force is applied to the end of the collar, the fingers of the hose fitting are induced to flare outwardly in a curled manner. With this device, contact is made with the ends of the fingers of the fitting. The chance of damage occurring to the ends of the fingers by using this device, before the fingers are spread outwardly, are reasonably high. Considerable force must be initially applied to the ends of the fingers of the fitting, which can cause damage before the fingers are urged to curl outwardly and spread. In the Scudieri design, it is also not certain that the fingers of the fitting will not simply collapse when a force is applied at the remote end of the collar. One or more of the fingers may simply shrivel, rather than spread outwardly in a smooth manner. Scudieri includes a raised curved interior rim, which is designed to induce the ends of the fitting fingers to spread outwardly, but it is not evident that the spreading action will occur smoothly without damage to the ends of the fingers. Scudieri does not utilize a hose flare or balloon action to persuade the fingers to be spread outwardly. Further, Scudieri does not include a rod which is inserted into the interior of the hose to prevent the hose from collapsing internally.
Bagby, U.S. Pat. No. 3,787,950, Jan. 29, 1974, shows a rod and flange combination which are used to push the fitting off the end of the hydraulic hose. Bagby includes a hose grip which purportedly holds the hose securely. However, since tremendous forces are required in order to push a fitting off the end of a hydraulic hose, it is not clear that the grip will hold the hose securely under such tremendous forces. Bagby includes teeth on the interior of his gripping mechanism but it is doubtful those teeth will exert a strong enough gripping action to withstand the forces required in order to push the fitting from the end of the hose. Bagby discloses a rod which fits inside the hose, the rod being used to push the interior portion of the fitting (the stem) in a direction away from the end of the hose. Since the rod, which has a plunger at the end, impinges on the interior stem of the hose fitting, there is a good chance that under the high forces utilized, damage to the stem of the fitting will occur. Then, if the fitting is successfully removed, and installed on a new hose, the damaged ends of the stem will score the interior of the hydraulic hose, which will ultimately lead to premature failure of the new hose.
Strybel, U.S. Pat. No. 4,213,216, granted Jul. 22, 1980, discloses a service tool structure for use in servicing charging hose and fittings provided with adjustable core depressors for controlling the valve means thereof. Strybel's service tool provides simplified installation and removal of the end-fitting gaskets. His service tool also provides facilitated adjustment of the adjustable "depressor" and may include means defining a "storage cavity" for maintaining spare gaskets and core depressors.
The Strybel invention relates to the servicing of a "low-pressure", "crimped" hose and valve assembly used on air lines, fuels and/or gages such as propane, natural gas, nitogen and helium, as shown in FIGS. 4, 14, and 16, and in the illustrated embodiment. The hose coupling includes a nipple 14 installed on the distal end 15 of a hose, such as an air hose, as by suitable "crimped" connector 16. Strybel's tool is therefore useful for tubed tires with valves.